Whole time alto was performing (5)
I believe the answer is:
total
'whole' is the definition.
(similar in meaning)
'time alto was performing' is the wordplay.
I cannot quite see how this works, but
'time' could be 't' (abbreviation) and 't' is present in the answer.
an anagram of 'alto' is 'otal' which is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for total that I've seen before include "Ruin" , "Unqualified" , "It might be grand" , "The whole number" , "Count" .)